Global Context of the Galileo-E6 Observations of Jupiter's White Ovals

A.A. Simon, R.F. Beebe (NMSU), P.J. Gierasch (Cornell University), Galileo SSI Team

In May 1997, the Galileo SSI Team obtained observations of a small portion of Jupiter near tex2html_wrap_inline11 S planetographic latitude, which contains the long-lived White Ovals: FA, DE and BC. Due to data transmission constraints, the observations were limited to a region centered on a cyclonic system between BC and DE. This Galileo data has been supplemented by a time-sequence of HST WFPC2 data, which was obtained to a provide temporal and global context of interpreting the spatially limited, high-resolution Galileo data. As part of the HST campaign, data have been obtained on July 15, '94, July 23, '94, Aug. 24, '94, Feb. 17, '95, Oct. 5, '95, May 14, '96, Oct. 21, '96, April 4, '97 and May 6, '97. Over this epoch, Oval BC drifted eastward relative to System III longitude at a rate of tex2html_wrap_inline13 /day. The data were mapped into an inertial frame-of-reference rotating at a rate tex2html_wrap_inline15 /day faster than System III. Within this system, DE shifted eastward tex2html_wrap_inline17 in 994 days (July '94 - April '97) and the morphology of the intervening cyclonic system varied. Over the same epoch, anticyclonic features W1, W2 and FA, initially spanning a longitudinal region of tex2html_wrap_inline19 to tex2html_wrap_inline21 west of DE, encroached on DE and a third system to the east of BC strengthened, resulting in an alternating pattern of six cyclonic-anticyclonic cloud systems spanning a longitudinal range of tex2html_wrap_inline21 on Oct. 21, '96. Relative heights and cloud interactions have been derived from the Galileo data and this system is discussed in terms of the local wind field and historical record.

This work was supported by grants GO5313.01-93A, GO6009.01-94A, and GO6452.01-95A from STScI, operated by AURA, Inc. under contract NAS5-26555.